Problem: $ { \left[\begin{array}{rr}{-1} & {0} \\ {-2} & {3} \\ {1} & {1}\end{array}\right]+\left[\begin{array}{rr}{-2} & {4} \\ {3} & {-1} \\ {1} & {1}\end{array}\right] = {?} } $
Answer: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}+{-2} & {0}+{4} \\ {-2}+{3} & {3}+{-1} \\ {1}+{1} & {1}+{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-3} & {4} \\ {1} & {2} \\ {2} & {2}\end{array}\right]}$